The module containing all the different types of channels in CHP. Unlike
JCSP and C++CSP2, CHP does not offer buffered channels directly (see the
Control.Concurrent.CHP.Buffers module). There are four different channel types, effectively
all possible combinations of:

It is possible for the type system to infer which channel you want when
you use newChannel. If the types of the ends are known by the type system,
the channel-type can be inferred. So you can usually just write newChannel,
and depending on how you use the channel, the type system will figure out
which one you needed.

A class used for allocating new channels, and getting the reading and
writing ends. There is a bijective assocation between the channel, and
its pair of end types. You can see the types in the list of instances below.
Thus, newChannel may be used, and the compiler will infer which type of
channel is required based on what end-types you get from reader and writer.
Alternatively, if you explicitly type the return of newChannel, it will
be definite which ends you will use. If you do want to fix the type of
the channel you are using when you allocate it, consider using one of the
many oneToOneChannel-like shorthand functions that fix the type.

This is useful when you want to write worker processes that evaluate data
and send it back to some "harvester" process. By default the values sent
back may be unevaluated, and thus the harvester might end up doing the evaluation.
If you use this function, the value is guaranteed to be completely evaluated
before sending.

Like newChannel but also associates a label with that channel in a
trace. You can use this function whether tracing is turned on or not,
so if you ever use tracing, you should use this rather than newChannel.

A helper class for easily creating several channels of the same type.
The same type refers not only to what type the channel carries, but
also to the type of channel (one-to-one no poison, one-to-any with
poison, etc). You can write code like this:

Claims the given channel-end, executes the given block, then releases
the channel-end and returns the output value. If poison or an IO
exception is thrown inside the block, the channel is released and the
poison/exception re-thrown.